SINGAPORE (Reuter) - A drifting supertanker spewed burning oil and spread a slick two miles long off Sumatra yesterday, as pollution experts flew in to fight a threat to hundreds of species of the region's marine life.

A spokesman for the Danish owner of the abandoned 255,312-tonne Maersk Navigator, which carries nearly 2 million barrels of oil, said the oil slick had formed north of the Indonesian island.

'We have reports that the Maersk Navigator is spilling burning oil from the ruptured cargo tank on the port side in the middle of the ship,' the A P Moller spokesman said.

The Singapore-registered Maersk Navigator, built in 1989, was en route from Oman to Japan when it collided with the 96,545-tonne empty tanker Sanko Honour in the Andaman Sea. Environmentalists said endangered leatherback and hawksbill turtles, and the dugong, a gentle mammal thought to be the origin of tales of mermaids, could be at risk. 'We are very, very worried. The consequences could be irreversible,' said Mohamad Idris, Malaysian president of Friends of the Earth.